EAGER: Chasing the elusive syntrophic partners in direct interspecies electron transfer

EAGER：在直接种间电子转移中追逐难以捉摸的互养伙伴

• 批准号: 2128365
• 负责人: Heyang Yuan
• 金额: $ 24.99万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2128365&HistoricalAwards=false
• 关键词: EAGER; Chasing; elusive; syntrophic; partners

Anaerobic digestion is widely utilized worlwide to treat waste streams and convert them to biogas such as methane. Biogas fom anerobic digestion typically consists of 50-70% methane and thus needs to be treated to remove impurities including carbon dioxide and water vapor. To eliminate the need for addtional treatment and purification of biogas from existing anaerobic digesters, it is critical to understand and quantify the metabolic pathways of the microbial consortial involved in biogas production. The overarching goal of this high-risk and high-reward EAGER project is to characterize and quantify the metabolic pathways that drive methane production during anaerobic digestion. To advance this goal, the Principal Investigator (PI) of this project proposes to carry out an integrated experimental research program to test the hypothesis that interspecies hydrogen transfer (IHT) and direct interspecies electron transfer (DIET) play an equally important role during biogas production by methanogenesis in electrically conductive environments. The successful completion of this EAGER project could provide new fundamental knowledge that could be leveraged to develop and implement new engineering reactor design and operational strategies to increase the methane content of biogas produced by anaerobic digestors. Further benefits to society will be achieved through student education and training including the mentoring of a doctoral student. Interspecies hydrogen transfer (IHT) and direct interspecies electron transfer (DIET) have been shown to contribute to biogas production by methanogenesis in electrically conductive environments. However, a fundamental understanding and quantification of the relative contributions of IHT and DIET to methanogenesis have remained elusive due to the lack of experimental techniques to directly measure the associated microbial metabolisms and activities. The overarching goal of this project is to address this knowledge gap. To advance this goal, the Principal Investigator (PI) of this project hypothesizes that IHT and DIET play an equally important role during biogas production by methanogenesis in electrically conductive environments. This hypothesis is based on the results of preliminary studies by the PI that identified a novel Geobacter species (Candidatus Geobacter eutrophica) that was abundant in anerobic reactors supplied with conductive granular activated carbon. The PI also found that the Candidatus Geobacter eutrophica bacteria actively expressed genes encoding proteins for both extracellular electron transfer and hydrogen metabolism. To test this new hypothesis, the PI proposes to carry out an integrated experimental research program structured around two specific aims: 1) enrich DIET-capable Geobacter bacteria and elucidate their extracellular electron transfer mechanisms (Specific Aim 1) and 2) enrich DIET-capable methanogens and characterize their extracellular electron uptake mechanisms (Specific Aim 2). To enrich the DIET-capable Geobacter and methanogen bacteria, the PI proposes to use electrochemical stimulation in bioelectrochemical systems with specially designed electrodes. By combining cyclic voltammetry with measurements of biogas production, ion chromatography, resonance Raman microscopy and omics (metagenomics and metatranscriptomics), the PI hopes to unravel the metabolic pathways responsible for DIET in both electron-donating and electron-accepting microbial partners. The successful completion of this project has the potential for transformative impact through the generation of new fundamental knowledge to advance the development of new bioprocesses such as electro-methanogenesis that could convert waste streams to biogas with much higher methane yields than existing anerobic digestion reactors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

厌氧消化被广泛用于治疗废物流并将其转换为沼气等沼气。 FOM厌食症消化通常由50-70％甲烷组成，因此需要处理以去除包括二氧化碳和水蒸气在内的杂质。为了消除现有厌氧消化园的沼气添加治疗的需求，了解和量化与沼气生产有关的微生物联盟的代谢途径至关重要。这个高风险和高回报的渴望项目的总体目标是表征和量化在厌氧消化过程中驱动甲烷产生的代谢途径。为了促进这一目标，该项目的主要研究者（PI）提议执行一项综合的实验研究计划，以测试种间氢转移（IHT）和直接种间种间电子转移（饮食）的假设，在电导环境中通过甲烷生成在生产中发挥同样重要的作用。这个急切的项目的成功完成可能会提供新的基本知识，这些知识可以利用，以开发和实施新的工程反应堆设计和操作策略，以增加厌氧消化园产生的沼气的甲烷含量。通过学生的教育和培训，包括指导博士生，将对社会获得进一步的好处。种间种间氢转移（IHT）和直接种间电子转移（饮食）已被证明在电导环境中通过甲烷发生有助于产生沼气。但是，由于缺乏直接测量相关的微生物代谢和活性的实验技术，对IHT和饮食对甲烷生成的相对贡献的基本了解和量化仍然难以捉摸。该项目的总体目标是解决这一知识差距。为了促进这一目标，该项目的主要研究者（PI）假设IHT和饮食在甲烷生成在电导环境中通过甲烷生成在沼气生产过程中起同样的重要作用。该假设基于PI的初步研究结果，PI鉴定出了一种新型的地理细菌（Candidatus geobacter forrophica），该物种在提供的厌氧反应器中丰富，并提供了带有导电性颗粒状活性碳的厌氧反应器。 PI还发现，念珠菌的富富菌细菌积极表达了编码细胞外电子转移和氢代谢的蛋白质的基因。为了检验这一新的假设，PI提议执行围绕两个具体目的构建的集成实验研究计划：1）富集具有饮食能力的地理细菌并阐明其细胞外电子传递机制（特定目标1）和2）富集饮食能力的甲基植物，并表征其细胞外电子含量的特定含量，并表征其特定的电子含量（特定的EAMISIS）。为了丰富具有饮食能力的地理细菌和甲烷原细菌，PI建议在具有特殊设计的电极的生物电化学系统中使用电化学刺激。通过将循环伏安法与沼气产生，离子色谱，共振拉曼显微镜和法仪（元基因组学和元文字组合学）的测量结合在一起，PI希望能够阐明负责电子染料和电子载量的微生物伴侣的代谢途径。该项目的成功完成可以通过产生新的基本知识来推动新生物准则的发展，例如电甲烷生成等新的生物准则的发展，可以将废物流转化为甲烷产量要高得多的淡虫消化反应堆的沼气，这比NSF的法定任务及其范围的范围通过评估的范围来弥补，这表明了NSF的法规范围的范围。